GraphViz::Regex - Visualise a regular expression

       Leon Brocard <acme@astray.com>

       Note that this module relies on debugging information provided by Perl, and is known to fail on at least
       two versions of Perl: 5.005_03 and 5.7.1. Sorry about that - please use a more recent version of Perl if
       you want to use this module.

       Copyright (C) 2000-1, Leon Brocard

       This module is free software; you can redistribute it or modify it under the Perl License, a copy of
       which is available at <http://dev.perl.org/licenses/>.

perl v5.30.3                                       2020-07-22                               GraphViz::Regex(3pm)

       This module attempts to visualise a Perl regular expression. Understanding regular expressions is tricky
       at the best of times, and regexess almost always evolve in ways unforseen at the start. This module aims
       to visualise a regex as a graph in order to make the structure clear and aid in understanding the regex.

       The graph visualises how the Perl regular expression engine attempts to match the regex. Simple text
       matches or character classes are represented by.box-shaped nodes. Alternations are represented by a
       diamond-shaped node which points to the alternations. Repetitions are represented by self-edges with a
       label of the repetition type (the nodes being repeated are pointed to be a full edge, a dotted edge
       points to what to match after the repetition). Matched patterns (such as $1, $2, etc.) are represented by
       a 'START $1' .. 'END $1' node pair.

       This uses the GraphViz module to draw the graph.

new
       This is the constructor. It takes one mandatory argument, which is a string of the regular expression to
       be visualised. A GraphViz object is returned.

         my $graph = GraphViz::Regex->new($regex);

   as_*
       The regex can be visualised in a number of different graphical formats. Methods include as_ps, as_hpgl,
       as_pcl, as_mif, as_pic, as_gd, as_gd2, as_gif, as_jpeg, as_png, as_wbmp, as_ismap, as_imap, as_vrml,
       as_vtx, as_mp, as_fig, as_svg. See the GraphViz documentation for more information. The two most common
       methods are:

         # Print out a PNG-format file
         print $g->as_png;

         # Print out a PostScript-format file
         print $g->as_ps;

       GraphViz::Regex - Visualise a regular expression

         use GraphViz::Regex;

         my $regex = '(([abcd0-9])|(foo))';

         my $graph = GraphViz::Regex->new($regex);
         print $graph->as_png;